Effects of pH on the Growth of Staphylococcus aureus, Streptococcus agalactiae, and Escherichia coli species

Pam Shelton

Biology Undergraduate, Health Science Concentration

Tennessee Technological University

Project Summary Harmful bacteria in environement Helpful to know about their growth

Monitor growth of pathogens at varying pH levels

Expect each organism will have different optimal pH

Expect organisms will have similar ranges

Introduction/Background Staphylococcus aureus

• “responsible for a wide range of human disease, including septicemia; endocarditis and pneumonia; and wound, bone and joint infection (Feil et al 2003).”

• “associated with nosocomial infections (Caiazza and O’Toole 2003).”

Introduction (cont)

Streptococcus agalactiae• Group B Streptococcus• “most common cause of bacterial infection in

the newborn (Curtis et al 2003).”• “leading cause of bacterial sepsis, pneumonia,

and meningitits in neonates (Tettlin et al 2002).”

Introduction (cont)

Escherichia coli• Associated with food products• “presence of feces on meat products is a

primary source of foodborne pathogens, such as Escherichia coli 0157:H7 (Ashby 2003).”

Introduction (cont)

All cause disease if present in large amounts or immune system is compromised

Learning about growth allows for development of ways to limit growth

Objective/Hypothesis Hypothesis: Various bacteria require

different pH levels in order to grow properly. Objective: To determine the pH range and

optimal pH for the growth of Staphylococcus aureus, Streptococcus agalactiae, and Escherichia coli

Methods and Material Tube growth method (Kelly et al 2003)

• Growth broth ranging from pH 0 to pH 14• Inoculate with bacteria• Incubate and Record growth• Narrow growth broth pH range (e.g. 7.0, 7.2,

7.4,etc)• Inoculate with bacteria• Incubate and Record growth

Link to Data Form

Methods/Materials (cont)

Method performed for each organism in three trials• Eliminates experimental error• Average of values used as final result

Held constant with each organism and trial• Amount of bacteria used for inoculation• Temperature of incubator• Time of incubation• Broth composition (except pH determinate)

Expected Results and Benefits

Each organism will prefer unique optimal pH• Significantly larger number of growth in this

tube pH ranges similar in all three organisms

• All will grow in a wide range of tubes• Yet, with varying amounts of growth

Information used to develop chemical nature of products (cleaners, soap, etc)

Project Timelines Topic Selection: Aug 20, 2003- Aug 27, 2003 Title Selection: Aug 20,2003- Sept 3, 2003 Research Matrix Development: Sept 3, 2003- present Locating Literature Reveiws: Sept 3, 2003 – present Hypothesis Development: Sept 10, 2003- Sept 17, 2003 Creating Data Forms: Sept 24, 2003- October 1, 2003 Power Point Presentation: Oct 1, 2003- present Research Proposal Development: Oct 1, 2003- present Research: Oct 15, 2003- Oct 29, 2003 Poster Development: Nov 5, 2003- Nov 12, 2003 Manuscript Preparation: Aug 20, 2003- Dec 3, 2003

Literature Cited Ashby, K., Wen, J., Chowdhury, P., Casey, T., Rasmussen, M., Petrich, J. 2003.

Fluorescence of dietary porphyrins as a basis for real-time detection of fecal contamination on meat. Journal of Agriculture and Food Chemistry 51: 3502-3507.

Caiazza, N., O’Toole, G. 2003. Alpha-toxin is required for biofilm formation by Staphylococcus aureus. Journal of Bacteriology 185: 3214-3217.

Curtis, J., Kim, G., Wehr, N., Levine, R. 2003. Group B Streptococcal phospholipid causes pulmonary hypertension. Proceedings of the National Academy of Sciences of the United States of America 100: 5087-5090.

Feil, E., Cooper, J., Grundmann, H., Robinson, D., Enright, M., Berendt, T., Peacock, S., Smith, J., Murphy, M., Spratt, B., Moore, C., Day, N. 2003. How clonal is Staphylococcus aureus? Journal of Bacteriology 185: 3307-3316.

Kelly, C., Rudd, J., Hobka, M. 2003. Effects of pH on mercury uptake by an aquatic bacterium: Implications for hg cycling. Environmental Science and Technology 37: 2941-2946.

Tettelin, H., Masignani, V., Cieslewicz, M., Eisen, J., Peterson, S., Wessels, M., Paulsen, I., Nelson, K., Margarit, I., Read, T., Madoff, L., Wolf, A., Beanan, M., Brinkac, L., Daugherty, S., DeBoy, R., Durkin, A., Kolonay, J., Madupu, R., Lewis, M., Radune, D., Fedorova, N., Scanlan, D., Khouri, H., Mulligan, S., Carty, H., Cline, R., Van Aken, S., Gill, J., Scarselli, M., Mariani, M., Vegni, F., Maione, D., Rinaudo, D., Rappuoli, R., Telford, J., Kasper, D., Grandi, G., Fraser, C. 2002. Complete genome sequence and comparative genomic analysis of an emerging human pathogen, serotype V Streptococcus agalactiae. Proceedings of the National Academy of Sciences of the United States of America 99: 12391-12396.